Ethylene vinyl acetate-dioctyl maleate-2-ethylhexyl acrylate interpolymers

ABSTRACT

Adhesive compositions having a Tg of -45° to -25° C. suitable for application to plasticized polyvinyl chloride comprising 25 to 40% by weight of an vinyl ester of a alkanoic acid; 10-30% by weight ethylene; 20 to 30% by weight of di-2-ethylhexyl maleate or fumarate; 20 to 30% by weight of 2-ethylhexyl acrylate; and 1 to 10% by weight of a mono-carboxylic acid.

This application is a division of application Ser. No. 07/169,632, filedMar. 17, 1988, U.S. Pat. No. 4,908,268.

BACKGROUND OF THE INVENTION

This invention relates to a process for the preparation of pressuresensitive adhesive compositions in general and especially to thoseadapted for use on vinyl substrates. The resultant adhesives comprisepolymers of ethylene, vinyl ester, di-2-ethylhexyl maleate or thecorresponding fumarate, 2-ethylhexyl acrylate, and an unsaturated mono-carboxylic acid.

Pressure-sensitive adhesives function to provide instantaneous adhesionwhen applied under light pressure. They are characterized by having abuilt-in capacity to secure this adhesion to a surface withoutactivation, such as by treatment with solvents or heat, and also byhaving sufficient internal strength so that the adhesive material willnot rupture before the bond between the adhesive material and thesurface ruptures. The capacity to obtain instantaneous adhesion isusually expressed as the amount of "tack" or "tackiness". Ordinarily itis desirable to obtain as much tack as possible without losing asignificant amount of internal strength (cohesion). The latter balanceof adhesive and cohesive properties has been difficult to obtain inadhesive polymers since monomers conventionally incorporated into thepolymers to increase the cohesive strength generally result in adecrease in adhesive tack.

A specific class of pressure sensitive adhesives are used on vinylsubstrates such as are utilized in a wide variety of industrialapplications including as vinyl roof tops in automobiles, for decorativetrim as in vinyl labels, and decals and in specialty types. Unlikecommon polyolefin films such a spolyethylene and polypropylene, thesepolyvinyl chloride (PVC) films by nature of their process requirementsand high glass transition temperature, require formulation with a numberof additives. Some of these are migratory components and will affect thelong-term performance of a vinyl decal or label. The amounts and typesof additives vary among vinyl formulations, therefore, a wide range ofvinyl characteristics are available. A typical flexible PVC filmformulation contains a number of additives including plasticizers.Plasticizers used include the migratory monomeric types such asphthalate esters (e.g., dioctylphthalate) or the less migratorypolymeric plasticizers (e.g., polyesters, epoxidized soybean oils).These applications require stringent requirements on the adhesivecomposition. In particular, the vinyl substrates contain substantialamounts of these plasticizers which tend to migrate into the adhesive,especially after aging, the migration of which will destroy the adhesiveand cause the bond to fail.

Thus, the use of adhesive-coated flexible polyvinylchloride films hastraditionally been plaqued, to various degrees, by deterioration ofproperties due to migration of plasticizer out of the PVC film into theadhesive coating. The degree to which this occurs is dependent on thePVC formulation and the adhesive used. In addition to resistance to thisplasticizer migration on aging, adhesives for use on vinyl decals mustalso possess the previously discussed high initial peel values bothcohesive and adhesive strength and must inhibit resistance to shrinkage.

Some of the problems encountered with pressure sensitive adhesives areparticularly exemplified in the area of adhesive coated plasticizedvinyl (PVC) substrates which are heavily influenced by the plasticizertype and level in a PVC film. These additives which allow use of PVC forflexible applications are a major cause of the deterioration of polymercoatings applied to PVC. As a result of their more migratory character,monomeric plasticizers will have a bigger effect on adhesive propertiesthan will polymeric plasticizers. All else being equal, the higher thecontent of monomeric plasticizer in a vinyl film, the more deteriorationexperienced by the adhesive-coated decal as a function of time. Theseproblems have been addressed in my copending application, Ser. No.009,450 filed Feb. 2, 1987 now U.S. Pat. No. 4,753,846. The compositionsclaimed in the latter application, while superior to those of the priorart, still leave room for improvement with respect to their cohesivestrength properties for certain applications involving vinyl substrates.

SUMMARY OF THE INVENTION

In accordance with the present invention, I have found that pressuresensitive adhesive compositions characterized by a superior balance ofadjhesive and cohesive properties can be prepared from an emulsioninterpolymer containing 25 to 40% by weight of a vinyl ester of analkanoic acid; 10 to 30% by weight ethylene; 20 to 30% by weight ofdi-2-ethylhexyl maleate or the corresponding fumarate; 20 to 30% byweight of 2-ethylhexyl acrylate; and 1 to 5% by weight of amonocarboxylic acid. In formulating these adhesives, it is critical thata specific semi-batch emulsion polymerization process be employed. Inaccordance therewith all the ethylene and vinyl ester are chargedinitially together with preferably 50, but up to 75%, of the lessreactive maleate monomer. The more reactive acrylate monomer, residualmaleate and other functional monomers are then added incrementally overthe course of the polymerization.

The resultant adhesives are characterized by an overall balance ofadhesive and cohesive properties even after storage of the adhesivecoated substrates. As such, the pressure sensitive adhesives findparticular application for adhering vinyl substrates and especially foruse as adhesives for vinyl decals where a combination of high peel andtack with superior cohesion is required to prevennt vinyl shrinkage onthe liner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The vinyl esters utilized herein are the esters of alkanoic acids havingfrom one to about 13 carbon atoms. Typical examples include; vinylformate, vinyl acetate, vinyl propionate, vinyl butyrate, vinylisobutyrate, vinyl valerate, vinyl-2-ethyl-hexanoate, vinylisooctanoate, vinyl nonanoate, vinyl decanoate, vinyl pivalate, vinylversatate, etc. Of the foregoing, vinyl acetate is the preferred monomerbecause of its ready availability and low cost. The vinyl ester ispresent in the copolymer in amounts of about 25 to 40% by weight,preferably 30 to 35%.

The specific dioctyl maleate isomer utilized herein is thedi-2-ethylhexyl maleate. Since, after polymerization, the structure ofthe fumarate and maleate (the cis and the isomers) are the same, thecorresponding fumarate ester is also contemplated for use herein. Thelatter component is present in the copolymer is amounts of about 20 to30% by weight, preferably about 25%.

Also herein is 2-ethylhexyl acrylate in an amount of 20 to 30% byweight, preferably about 25%, and ethylene in an amount of about 10-30%by weight, preferably 15-25%.

The unsaturated mono-carboxylic acids utilized herein include, forexample, acrylic and methacrylic acid or the half esters of maleic acidsuch as monoethyl, monobutyl or monooctyl maleate, with acrylic acid ormonoethyl maleate being preferred. The acid is present in an amount of 1to 5% by weight, preferably 2 to 4%.

It may also be desired to incorporate in the copolymer minor amounts ofone or more functional comonomers. Suitable copolymerizable comonomersinclude, for example, acrylamide, tertiary octylacrylamide, N-methylol(meth)-acrylamide, N-vinylpyrrolidinone, diallyl adipate, triallylcyanurate, butanediol diacrylate, allyl methacrylate, etc. as well as C₂-C₃ hydroxyalkyl esters such as hydroxyethyl acrylate, hydroxy propylacrylate and corresponding methacrylates. The latter comonomers aregenerally used at levels of less than about 5% depending upon the natureof the specific comonomer. In all cases, the T_(g) of the resultantpressure sensitive adhesive should be within the range of about -45° to-25° C. so the optional comonomers should not be added at levels whichwill result in polymers outside this T_(g) range.

In addition, certain copolymerizable monomers which assist in thestability of the copolymer emulsion, e.g., vinyl sulfonic acid, are alsouseful herein as latex stabilizers. These optionally present monomers,if employed, are added in very low amounts of from 0.1 to about 2% byweight of the monomer mixture.

In accordance with either the procedures utilized herein the vinylacetate, ethylene, maleate and acrylate monomers are polymerized in anaqueous medium under pressures not exceeding 100 atmospheres in thepresence of a catalyst and at least one emulsifying agent, the aqueoussystem being maintained by a suitable buffering agent at a pH of 2 to 6,the catalyst being added incrementally or continuously. Morespecifically, the vinyl acetate and 50 to 75% of the maleate aresuspended in water and are thoroughly agitated in the presence ofethylene under the working pressure to effect solution of the ethylenein the vinyl acetate and maleate up to the substantial limit of itssolubility under the condition existing in the reaction zone, while thevinyl acetate and maleate are gradually heated to polymerizationtemperature. The homogenization period is followed by a polymerizationperiod during which the catalyst, which consists of a main catalyst orinitiator, and may include an activator, is added incrementally orcontinuously together with the acrylate and remaining maleate orfunctional monomers. The monomers employed may be added either as puremonomer or as a premixed emulsion.

Suitable as polymerization catalysts are the water-solublefree-radical-formers generally used in emulsion polymerization, such ashydrogen peroxide, sodium persulfate, potassium persulfate and ammoniumpersulfate, as well as tert-butyl hydroperoxide, in amounts of between0.01 and 3% by weight, preferably 0.01 and 1% by weight based on thetotal amount of the emulsion. they can be used alone or together withreducing agents such as sodium formaldehyde-sulfoxylate, ferrous salts,sodium dithionite, sodium hydrogen sulfite, sodium sulfite, sodiumthiosulfate, as redoc catalysts in amounts of 0.01 to 3% by weight,preferably 0.01 to 1% by weight, based on the total amount of theemulsion. The free-radical-formers can be charged in the aqueousemulsifier solution or be added during the polymerization in doses.

The polymerization is carried out at a pH of between 2 and 7, preferablybetween 3 and 5. In order to maintain the pH range, it may be useful towork in the presence of customary buffer systems, for example, in thepresence of alkali metal acetate, metal carbonates, alkali metalphosphates. Polymerization regulators, like mercaptans, aldehydes,chloroform, ethylene chloride and trichloroethylene, can also be addedin some cases.

The emulsifying agents are those generally used in emulsionpolymerization, as well as optionally present protective colloids. It isalso possible to use emulsifiers alone or in mixtures with protectivecolloids.

The emulsifiers can be anionic, cationic, nonionic surface-activecompounds or mixtures thereof. Suitable anionic emulsifiers are, forexample, alkyl sulfonates, alkylaryl sulfonates, alkyl sulfates,sulfates of hydroxylalkanols, alkyl and alkylaryl disulfonates,sulfonated fatty acids, sulfates and phosphates of polyethyoxylatedalkanols and alkylphenols, as well as esters of sulfosuccinic acid.Suitable cationic emulsifiers are, for example, alkyl quaternaryammonium salts, and alkyl quaternary phosphonium salts. Examples ofsuitable non-ionic emulsifiers are the addition products of 5 to 50 molsof ethylene oxide adducted to straight-chain and branch-chain alkanolswith 6 to 22 carbon atoms, or alkylphenols, or higher fatty acids, orhigher fatty acid amides, or primary and secondary higher alkyl amines;as well as block copolymers of propylene oxide with ethylene oxide andmixtures thereof. When combinations of emulsifying agents are used, itis advantageous to use a relatively hydrophobic emulsifying agent incombination with a relatively hydrophilic agent. The amount ofemulsifiying agent is generally from about 1 to about 10, preferablyfrom about 2 to about 8, weight percent of the monomers used in thepolymerization.

The emulsifier used in the polymerization can also be added, in itsentirety, to the initial charge to the polymerizatin zone or a portionof the emulsifier, e.g. from 90 to 25 percent thereof, can be addedcontinuously or intermittently during polymerization.

Various protective colloids may also be used in place of or in additionto the emulsifiers described above. Suitable colloids include partiallyacetylated polyvinyl alcohol, e.g., up to 50 percent acetylated, casein,hydroxyethyl starch, carboxymethyl cellulose, gum arabic, and the like,as known in the art of synthetic emulsion polymer technology. Ingeneral, these colloids are used at levels of 0.05 to 4% by weight basedon the total emulsion.

The process of making the interpolymers of the invention generallycomprises the preparation of an aqueous solution containing at leastsome of the emulsifying agent and stabilizer, and the pH bufferingsystem. This aqueous solution and the initial charge of vinyl ester andmaleate are added to the polymerization vessel and ethylene pressure isapplied to the desired value. The quantity of ethylene entering into thecopolymer is influenced by the pressure, the agitation, and theviscosity of the polymerization medium. Thus, to increase the ethylenecontent of the copolymer, higher pressures are employed. A pressuure ofat least about 10 atmospheres is most suitably employed. As previouslymentioned, the mixture is thoroughyl agitated to dissolve the ethylene,agitation being continued until substantial equilbrium is achieved. Thisgenerally requires about 15 minutes. However, less time may be requireddepending upon the vessel, the efficiency of agitation, the specificsystem, and the like. When high ethylene contents are desired, a higherdegree of agitation should be employed. In any case, by measuring thepressure drop of the ethylene in conventional manner, the realization ofsubstantial equilibrium can be easily determined. Conveniently thecharge is brought to polymerization temperature during this agitationperiod. Agitation can be effected by shaking, by means of an agitator,or other known mechanism. The polymerization is then initiated byintroducing initial amounts of the catalyst, and of the activator whenused. After polymerization has started, the catalyst and the activatorare incrementally added as required to continue polymerization, and theacrylate, residual maleate and any minor functional monomers aresimilarly added.

The polymerization reaction is generally continued until the residualvinyl ester monomer content is below about 1%. The completed reactionproduct is then allowed to cool to about room temperature, while sealedfrom the atmosphere.

The adhesive emulsions are produced and used at relatively high solidscontents, e.g. between 35 and 70%, preferably not less than 50%,although they may be diluted with water if desired.

The particle size of the latex can be regulated by the quantity ofnonionic or anionic emulsifying agent or protective colloid employed. Toobtain smaller particles sizes, greater amounts of emulsifying agentsare used. As a general rule, the greater the amount of the emulsifyingagent employed, the smaller the average particle size.

If desired, conventional additives may be incorporated into the noveladhesives of our invention in order to modify the properties thereof.Among these additives may be included thickeners, fillers or pigments,such as talc and clay, small amounts of tackifiers, etc.

The emulsion adhesive is useful on any conventional tape or other facestock, especially vinyl substrates such as vinyl films or foils. Theadhesive may be applied using conventional techniques. Typical methodsinvolve application of the adhesive onto a release liner by use ofmechanical coating processes such as air knife, trailing blade, knifecoater, reverse roll or gravure coating techniques. The adhesive isallowed to dry at room temperature and then oven dried at about 250° F.for 10 minutes. The coated release liner may then be laminated to theface stock by a nip roll using pressure between a rubber roll and asteel roll. This technique effects a transfer of the adhesive mass tothe face stock with a minimum of penetration.

It will be apparent that various changes and modifications may be madein the embodiments of the invention described above, without departingfrom the scope of the invention, as defined in the appended claims, andit is intended therefore, that all matter contained in the foregoingdescription shall be interpreted as illustrative only and not aslimitative of the invention.

EXAMPLE 1

This example illustrates the polymerization method used in preparingpressure sensitive adhesives of the present invention.

To a 10 liter autoclave was charged 450 g (of a 20% W/W solution inwater) sodium alkylaryl polyethylene oxide sulphate (3 moles ethyleneoxide), 40 g (of a 70% W/W solution in water) alkyl aryl polyethyleneoxide (30 moles ethylene oxide), 90 g (of a 25% W/W solution in water)sodium vinyl sulphonate, 0.5 g osdium acetate, 2 g sodium formaldehydesulfoxate, 5 g (of a 1% W/W solution in water) ferrous sulphate solutionand 2250 g of water. After purging with nitrogen, 2000 g of vinylacetate and 500 g of di-2-ethylhexylmaleate were charged to the reactor.The reactor was then pressurized to 700 psi with ethylene andequilibrated at 50° C. for 15 minutes. The polymerization was thenstarted by metering in a solution of 40 g tertiary butylhydroperoxide in250 g of water and 25 g of sodium formaldehyde sulfoxylate in 250 gwater over 51/2 hrs.

Once a two degree exotherm occurred, a pre-emulsified mixture of 500 gof di-2-ethylhexylmaleate, 1000 g of 2-ethylhexylacrylate, 100 g ofacrylic acid, 100 g of hydroxypropylacrylate, 4 g dodecylmercaptan, 1 gsodium acetate, 300 g (of a 20% W/W solution in water) sodium alkyl arylpolyethylene oxide sulphate (3 moles ethylene oxide) and 40 g (of a 70%W/W solution in water) alkyl aryl polyethylene oxide (30 moles ethyleneoxide) in 400 g of water was added to the autoclave over 41/2 hrsuniformly.

The reaction temperature was allowed to rise to 70°-75° C. over 1 hr andkept at this temperature during the polymerization by means of externalcooling. At the end of the initiator slow additions, the product wastransferred to an evacuated vessel (30 liter) to remove residualethylene from the system. It was identified as emulsion 1.

Using the general procedure described above, additional emulsions wereprepared varying the amounts and/or monomeric compositions. The majorand minor monomers utilized and their respective amounts are shown inTable 1. In particular, examples 1, 2 and 3 show the semi-batchpolymerization process with varying levels of vinyl acetate and dioctylmaleate and with the preferred process of adding 50% of thedi-2-ethylhexyl maleate initially and 50% in the slow-addn. Example 16is a repeat of example 2. Examples 4 and 5 show two extremes of addingall the di-2-ethylhexyl maleate initially or all in the slow-addn. Forfurther comparison purposes, example 6 shows typical slow additionprocesses of the prior art while examples 7 and 8 show acrylate/EVAcompositions (no maleate) made via slow addition or semi-batchprocesses. Example 9 shows maleate/EVA composition (no 2-ethylhexylacrylate) made via batch process. Examples 10 and 11 show vinyl acrylicand competitive all acrylic products for comparison. Examples 12, 13,14, and 15 show the preferred process of the invention using differentfunctional (minor) monomers and carboxyl and/or varying levels ofcarboxyl functionality.

                                      TABLE I                                     __________________________________________________________________________    (Stage 1)                (Stage 2)                                            % INIT    % INIT                                                                             % INIT                                                                             % INIT                                                                             % SA                                                                              % SA                                                                              % SA % SA                                                                              Process*                                                                            Overall (%) Major                                                             Monomers                      Run No                                                                             VA   E    DOM  EHA  VA  E   DOM  EHA Type  EHA VA  DOM E                 __________________________________________________________________________    (1)  40   20   10   0    0   0   10   20  SB    20  40  20  20                (2)  35   20   10   0    0   0   10   25  SB    25  35  20  20                (3)  30   20   10   0    0   0   10   30  SB    30  30  20  20                (4)  35   20   20   0    0   0    0   25  SB    25  35  20  20                (5)  35   20    0   0    0   0   20   25  SB    25  35  20  20                (6)  3.5   2    2   2.5  31.5                                                                              18  18   22.5                                                                              SA    25  35  20  20                (7)  3.5   2   --   5    31.5                                                                              18  --   40  SA    45  35  --  20                (8)  35   20   --   --   --  --  --   45  SB    45  35  --  20                (9)  40   20   40   --   --  --  --   --  B     --  40  40  20                (10)                                      SA    65  35  --  --                (11)                                      Competitive Acrylic                                                           Composition                         (12) 35   20   10   0    0   0   10   25  SB    25  35  20  20                (13) 35   20   10   0    0   0   10   25  SB    25  35  20  20                (14) 35   20   10   0    0   0   10   25  SB    25  35  20  20                (15) 35   20   10   0    0   0   10   25  SB    25  35  20  20                (16) 35   20   10   0    0   0   10   25  SB    25  35  20  20                __________________________________________________________________________     *B = Batch                                                                    SB = Semibatch                                                                SA = Slow addition                                                            Key: EHA = 2 Ethylhexylacrylate                                               DOM = Di2-ethylhexyl Maleate                                                  VA = Vinyl Acetate                                                            E = Ethylene                                                                  Minor Monomers                                                                Runs 1 thru 9,16  2% acrylic acid/2% hydroxypropylacrylate                    Run 10  2% acrylic acid/3% hydroxypropylacrylate                              Run 12  2% acrylic acid                                                       Run 13  2% acrylic acid/2% methacrylic acid                                   Run 14  4% acrylic acid                                                       Run 15  2% acrylic acid/4% tertiary octyl acrylate   The emulsion             adhesives were then coated on a plasticized vinyl film and dried in an     oven for 5 minutes at 105° C. The resulting dry adhesive deposition     was 20 mg./in.sup.2. The coatings were then tested for peel strength     according to the Pressure Sensitive Tape Council, Test Method No. 1,     modified to vary the dwell time between placing the coating in contact     with the stainless steel test panel and measuring the peel strength. In     addition, the bonded test specimens were heat aged as indicated in Table     II to accelerate any tedency to lose adhesion on aging on the PVC     substrate due to plasticizer migration into the polymer. The aged peel     testing was carried out after 7 days aging at 70° C. and recovery     times of 20 minutes and 24 hours respectively. The percent shrinkage was     measured after aging 24 hours at 70° C. on release liner.

Tests were also performed to evaluate the viscoelastic properties of thepolymers. These viscoelastic properties are based on dynamic mechanicalanalysis (using a rheometer) of polymeric solids and provides arelationship between the polymer structure and product performance. Thisanalysis specifically involves simultaneously measuring a materialresponse to both elastic and viscous stress. Several quantities can becalculated from the measured strain and stresses. If the test is done ina shear geometry then shear moduli (G) are calculated. Tensile andbending tests measure tensile moduli (E).

For dynamic mechanical analysis, films are cast onto release paper,allowed to air dry one day, then placed in a 60° C. oven for two days.Final film thickness was approximately 2 mm. To obtain frequency sweeps,the films are scanned at room temperature (25° C.) from 0.1 to 100Rad/sec at a fixed strain (10%). Storage modulus (G'), viscous modulus(G") and complex viscosity (ETA) are then plotted.

The elastic modulus (G' or E') of a material is defined as the ratio ofthe elastic (inphase) stress to strain and relates to the materials'ability to store energy elastically. Similarly, the loss modulus (G" orE") of a material is the ratio of the viscous (out of phase) componentto the strain, and is related to the materials' ability to dissipatestress through heat. The ratio of these moduli (G"/G' or E"/E') isdefined as tan delta, and indicates the relative degree of viscous toelastic dissipation, or damping of the material. The complex viscosity,ETA, can also be defined from the shear moduli. This viscosity can berelated to the viscosity measured in a steady shear test by arelationship known as the Cox-Merz law.

Polymers suitable for use in pressure sensitive adhesive applicationsmust be highly viscoelatic. Thus a PSA should have an elastic modulus(G') level between 5×10⁴ and 2×10⁵ Pa at 1 rad/s. This providessufficient deformation for good flow into a new substrate in shortcontact times. It is also sufficiently rigid for low creepcharacteristics at long times.

The results presented in Table II show the superior retention ofadhesive properties of the instant polymers (compared to those of theprior art) when subjected to aging on PVC film (vinyl). This isspecifically shown by Examples 1, 2, 3 and 16, and especially Examples 2and 16, the latter illustrating the high initial peel strengths (3-4lbs.) and retention of 2.5 to 3 lbs. of this peel strength on agingrelative to the EVA acrylates of the prior art (Examples 7 and 8) andvinyl acrylic current technology (Examples 10 and 11) of 3-4 lb. initialpeel strength but lower retention of peel strength on aging of only 1-2lb.

The test results also show that functional monomers are needed whereinitial peel strength is desired (see Examples 2, 12, 13, 14, 15 and 16which show the effects of varying the amounts of functional monomer).

The test results also show the preferred polymerization procedure to bethat described in Example 2 where the dioctyl maleate charge isapproximately equally distributed between the initial charge and theslow addition charge. This process provides and adhesive polymercharacterized by high initial peel (>3.5 lbs), good retention on aging(>2.5 lbs) and low shrinkage on the liner (below or equal to 1% CD orMD). The differences observed in the adhesive polymer of Example 2 ascompared with Example 4 (all dioctylmaleate added initially), Example 5(slow addition of dioctyl maleate) and Example 6 (slow addition of allmonomers) is also shown in the rheometric evaluation of the viscoelasticproperties as repeated below.

    ______________________________________                                        Tan                                                                           Delta         G' × 10.sup.5                                                                    G" × 10.sup.5                                                                       ETA × 10.sup.6                       ______________________________________                                        Example 2                                                                             0.68      2.24     1.52      2.70                                     Example 4                                                                             0.81      1.04     0.84      1.34                                     Example 5                                                                             0.52      1.71     0.89      1.93                                     Example 6                                                                             0.56      1.04     0.58      1.19                                     ______________________________________                                    

Now that the preferred embodiments of the present invention have beendescribed in detail, various modifications and improvements thereon willbecome readily apparent to those skilled in the art. Acccordingly, thespirit and scope of the present invention is to be limited only by theappended claims, and not be the foregoing disclosure.

                                      TABLE II                                    __________________________________________________________________________    End Use Performance Data          Rheometrics Data                            INITIAL PEEL (lb)                                                                           AGED PEEL (lb)                                                                          SHRINKAGE (%)          (AT 1 RAD/SEC)                 EX 20 Min.                                                                             24 Hrs.                                                                            20 Min.                                                                            24 Hrs.                                                                            M.D. C.D. TAN DELTA                                                                             G' × 10.sup.5                                                                G × 10.sup.5                                                                 ETA                       __________________________________________________________________________                                                        × 10.sup.6          1  1.9   3.1  2.3  3.0  0.32 0.56 0.68    2.63 1.79 3.18                      2  4.3   5.2  3.2  3.8  0.46 0.85 0.68    2.24 1.52 2.70                      3  2.8   4.7  1.6  2.9  0.84 1.20 0.57    1.82 1.05 2.10                      4  3.4   5.8  2.4  3.9  1.00 2.00 0.81    1.04 0.84 1.34                      5  2.4   2.7  1.1  1.8  1.00 1.94 0.52    1.71 0.89 1.93                      6  3.1   5.9  3.4  3.7  1.06 1.92 0.56    1.04 0.58 1.19                      7  2.4   4.6  1.2  1.8  0.86 1.08 0.43    2.98 1.28 3.24                      8  1.2   1.7  0.4  1.3  0.66 0.66 0.41    4.70 1.92 5.08                      9  3.1   5.0  2.8  3.1  1.36 2.16 0.86    1.81 1.56 2.39                      10 3.4   4.2  1.2  1.9   .56  .54 0.37    2.97 1.10 3.13                      11 3.2   4.4  1.2  2.9   .48  .54 0.56    2.80 1.58 3.21                      12 2.3   3.9  2.7  2.9   .78  .78 0.64    1.64 1.06 1.96                      13 3.6   5.3  3.1  3.0  1.05 1.29 0.70    2.40 1.69 2.94                      14 3.4   5.0  2.4  3.5  1.02 0.96 0.67    2.18 1.45 2.62                      15 3.7   5.0  2.9  3.3  0.95 0.97 0.61    3.27 1.99 3.82                      16 3.6   4.4  2.7  4.1  0.37 0.61 0.68    2.24 1.52 2.70                      __________________________________________________________________________     Notes                                                                         Tan Delta = Ratio G"/G'-                                                      ETA = Complex Viscosity                                                       G' = Elastic Modulus                                                          G" = Loss Modulus                                                             MD = Machine Direction                                                        CD = Cross Direction                                                     

I claim:
 1. Pressure sensitive adhesive compositions having a Tg of -45° to -25° C. suitable for application to plasticized polyvinylchloride films consisting essentially of 25-40% by weight a vinyl esterof a alkanoic acid; 10-30% by weight ethylene; 20 to 30% by weight ofdi-2-ethylhexyl maleate or fumarate; 20 to 30% dry weight of2-ethylhexyl acrylate; 1 to 10% by weight of a mono-carboxylic acid and0-10% of at least one copolymerizable comonomer selected from the groupconsisting of acrylamide, N-methylol (meth)-acrylamide,N-vinylpyrrolidinone, diallyl adipate, triallyl cyanurate, butanedioldiacrylate, tertiary octylacrylamide, hydroxyethyl acrylate,hydroxypropyl acrylate and the corresponding methacrylates.
 2. Theadhesive of claim 1 wherein the vinyl ester is vinyl acetate.
 3. Theadhesive of claim 1 wherein the maleate is di-2-ethyl hexyl maleate isemployed and is present in an amount of about 25 by weight.
 4. Theadhesive of claim 1 wherein the copolymerizable comonomer ishydroxyethyl acrlate or hydroxypropyl acrylate.
 5. The adhesive of claim1 wherein the vinyl ester is selected from the group consisting of vinylformate, vinyl acetate, vinyl propionate, vinyl butyrate, vinylisobutyrate, vinyl valerate, vinyl-2-ethyl-hexanoate, vinylisooctanoate, vinyl nonanoate, vinyl decanoate, vinyl pivalate, andvinyl versatate.
 6. The adhesive of claim 1 wherein the vinyl ester ispresent in an amount of 30 to 35% by weight.
 7. The adhesive of claim 3,wherein the 2-ethylhexyl acrylate is present in an amount of about 25%by weight.
 8. The adhesive of claim 1 wherein the acid is acrylic ormonoethyl maleate.
 9. The adhesive of claim 1 additionally containing upto 5% of at least the copolymerizable comonomer.